cookie实例-最近浏览记录

该程序实现显示最近的浏览记录，当点击书名链接时可查看关于该书的详细信息，返回后可在最近的浏览列表中查看浏览记录，最后点击的出现在最前面。

1.创建基本类Book存储基本数据

  1: package net.csing;
  2: 
  3: public class Book {
  4:   public Book(){}
  5:   
  6:   public Book(String id,String name, String auth, String price, String publish,
  7:       String description) {
  8:     super();
  9:     this.id=id;
 10:     this.name = name;
 11:     this.auth = auth;
 12:     this.price = price;
 13:     this.publish = publish;
 14:     this.description = description;
 15:   }
 16:   private String id;
 17:   private String name;
 18:   private String auth;
 19:   private String price;
 20:   private String publish;
 21:   private String description;
 22:   
 23:   public String getId() {
 24:     return id;
 25:   }
 26:   
 27:   public void setId(String id) {
 28:     this.id = id;
 29:   }
 30:   public String getName() {
 31:     return name;
 32:   }
 33:   public void setName(String name) {
 34:     this.name = name;
 35:   }
 36:   public String getAuth() {
 37:     return auth;
 38:   }
 39:   public void setAuth(String auth) {
 40:     this.auth = auth;
 41:   }
 42:   public String getPrice() {
 43:     return price;
 44:   }
 45:   public void setPrice(String price) {
 46:     this.price = price;
 47:   }
 48:   public String getPublish() {
 49:     return publish;
 50:   }
 51:   public void setPublish(String publish) {
 52:     this.publish = publish;
 53:   }
 54:   public String getDescription() {
 55:     return description;
 56:   }
 57:   public void setDescription(String description) {
 58:     this.description = description;
 59:   }
 60: 
 61:   @Override
 62:   public String toString() {
 63:     return "[name=" + name + ", auth=" + auth + ", price=" + price
 64:         + ", publish=" + publish + ", description=" + description + "]";
 65:   }
 66: }
 67: 

2.创建BookDao类来操作Book数据并初始化要显示的book列表：

  1: package net.csing;
  2: 
  3: import java.util.LinkedHashMap;
  4: import java.util.Map;
  5: 
  6: public class BookDao {
  7:   private static Map<String, Book> map=new LinkedHashMap<String, Book>();
  8:   public BookDao(){};
  9:   static{
 10:     map.put("1", new Book("1","三国演义","99.0","朴乾","黑马出版社","一群男人纠结不清的故事...."));
 11:     map.put("2", new Book("2","西游记","10.0","曹睿","传智出版社","一个和尚一个猴子一头猪和一个秃子去西天的故事..."));
 12:     map.put("3", new Book("3","水浒传","2.0","奥巴马","人民教育出版社","105个男人和3个女人闯荡江湖的故事"));
 13:     map.put("4", new Book("4","金瓶梅","200.0","哈利波特","科技出版社","混乱不堪的故事..."));
 14:     map.put("5", new Book("5","逆行","3.0","高深","人民教育出版社","我们逆行"));
 15:   }
 16:   //根据id得到书；
 17:   public static Book getBookById(String id){
 18:     return map.get(id);
 19:   }
 20:   //获得所有的书的集合；
 21:   public static Map<String,Book> getAllBook(){
 22:     return map;
 23:   }
 24: }
 25: 

3.显示全部书籍的列表以及最近的浏览记录

  1: package net.csing;
  2: 
  3: import java.io.IOException;
  4: import java.io.Writer;
  5: import java.util.Iterator;
  6: import java.util.Map;
  7: import java.util.Map.Entry;
  8: import java.util.Set;
  9: 
 10: import javax.servlet.ServletException;
 11: import javax.servlet.http.Cookie;
 12: import javax.servlet.http.HttpServlet;
 13: import javax.servlet.http.HttpServletRequest;
 14: import javax.servlet.http.HttpServletResponse;
 15: 
 16: public class Index extends HttpServlet {
 17: 
 18:   public void doGet(HttpServletRequest request, HttpServletResponse response)
 19:       throws ServletException, IOException {
 20: 
 21:     //解决中文乱码问题；
 22:     response.setContentType("text/html;charset=utf-8");
 23:     
 24:     Writer outer=response.getWriter();
 25:     outer.write("本站的所有书籍如下：<br>");
 26:     //从类的方法中获得所有的书，并遍历；
 27:     Map<String, Book> map=BookDao.getAllBook();
 28:     Set<Entry<String, Book>> set=map.entrySet();
 29:     Iterator<Entry<String,Book>> iterator=set.iterator();
 30:     while(iterator.hasNext()){
 31:       Entry<String, Book> entry=iterator.next();
 32:       //String idString=entry.getKey();
 33:       Book book=entry.getValue();
 34:       //将取得书以链接列表的形式打印到浏览器页面中。
 35:       //在链接页面的地址中返回该链接书的id
 36:       outer.write("<a href='"+request.getContextPath()+"/servlet/Info?id="+book.getId()+"'>"+book.getName()+"</a><br>");
 37:     }
 38:     outer.write("<hr>");
 39:     //获得cookie信息，以便查看之前的浏览记录。
 40:     Cookie[] cookie=request.getCookies();
 41:     //设置对应的浏览记录；
 42:     Cookie findCookie=null;
 43:     //判断cookie是否为空。
 44:     if(cookie==null){
 45:       outer.write("您尚未浏览过本站的图书...");
 46:     }
 47:     //cookie不为空时查看是否有符合条件的浏览记录
 48:     else if(cookie!=null){
 49:       for(Cookie c:cookie){
 50:         if("history".equals(c.getName())){
 51:           findCookie=c;
 52:           break;
 53:         }
 54:       }
 55:     }
 56:     //如果有浏览记录，则分拆该值得到id并获取书名。
 57:     if(findCookie!=null){
 58:       outer.write("您最近浏览过的书籍如下："+"<br><br>");
 59:       String[] bookid=findCookie.getValue().split("-");
 60:       for(String id:bookid){
 61:         outer.write(BookDao.getBookById(id).getName()+"<br>");
 62:       }
 63:     }
 64:   }
 65: 
 66:   public void doPost(HttpServletRequest request, HttpServletResponse response)
 67:       throws ServletException, IOException {
 68: 
 69:     response.setContentType("text/html");
 70: 
 71:   }
 72: 
 73: }
 74: 

4.对于每一本书籍，显示该书的详细信息：

  1: package net.csing;
  2: 
  3: import java.io.IOException;
  4: import java.io.Writer;
  5: 
  6: import javax.servlet.ServletException;
  7: import javax.servlet.http.Cookie;
  8: import javax.servlet.http.HttpServlet;
  9: import javax.servlet.http.HttpServletRequest;
 10: import javax.servlet.http.HttpServletResponse;
 11: 
 12: public class Info extends HttpServlet {
 13: 
 14:   public void doGet(HttpServletRequest request, HttpServletResponse response)
 15:       throws ServletException, IOException {
 16: 
 17:     response.setContentType("text/html;charset=utf-8");
 18:     Writer outer=response.getWriter();
 19:     
 20:     //根据请求信息中的id获得请求的书名id
 21:     String idString=request.getParameter("id");
 22:     //打印书信息；
 23:     outer.write(BookDao.getBookById(idString).toString()+"<a href='"+request.getContextPath()+"/servlet/Index"+"'>返回</a>");
 24:     //获得所有的cookie
 25:     Cookie[] cookies=request.getCookies();
 26:     Cookie findCookie=null;
 27:     //创建stringbuffered存储临时的id字段串；
 28:     StringBuffer idBuffer=new StringBuffer();
 29:     //只有当cookie不为空时的判断才有意义。
 30:     if(cookies!=null){
 31:       //遍历并查找对应的cookie浏览记录。
 32:       for(Cookie c:cookies){
 33:         if("history".equals(c.getName())){
 34:           findCookie=c;
 35:           break;
 36:         }
 37:       }
 38:     }
 39:     //不管cookies是否为空，我们都需要判断是否查找到对应的浏览历史cookie。
 40:     if(findCookie==null){
 41:       idBuffer.append(idString);
 42:     }
 43:     else{
 44:       String[] find=findCookie.getValue().split("-");
 45:       //将最近的书的id放在stringbuffered的最前面，现存的依次添加到后面，这个方法简直太棒了。
 46:       idBuffer.append(idString);
 47:       //依次将现存的id添加到buffered中，并且限制了id的长度。
 48:       for(int x=0;(x<find.length)&&(idBuffer.toString().split("-").length<3);x++){
 49:         //之前浏览的id值和当前浏览的值不相同时才添加。
 50:         if(!idString.equals(find[x])){
 51:           idBuffer.append("-"+find[x]);
 52:         }
 53:       }
 54:     }
 55:     //将获取的id浏览记录字段串添加到对应的cookie中。
 56:     Cookie cookie=new Cookie("history", idBuffer.toString());
 57:     //设置cookie存活时间以及存储路径。
 58:     cookie.setMaxAge(Integer.MAX_VALUE);
 59:     cookie.setPath(request.getContextPath());
 60:     //将获取好的cookie存储到客户端浏览器中。
 61:     response.addCookie(cookie);
 62:   }
 63: 
 64:   public void doPost(HttpServletRequest request, HttpServletResponse response)
 65:       throws ServletException, IOException {
 66: 
 67:     response.setContentType("text/html");
 68: 
 69:   }
 70: 
 71: }
 72: 

5.最终效果图如下：

刚打开时的界面：

浏览后的界面：